
import java.util.Scanner;

public  class FloatingpointBinary {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        double x=sc.nextInt();
        double l=0,r=x;
        while (r-l>1e-8){
            double mid=(l+r)/2;
            if(mid*mid>=x) r=mid;
            else l=mid;
        }
        System.out.printf("%.6f\n",l);

    }
}